Thanks, Robert! Just out of curiosity, how dry did you dry your furniture lumber? Tangential shrinkage is always much greater that radial shrinkage and is responsible for most of the cupping and much of the splitting. 12% is a good target and close to equilibrium moisture content in much of the USA. 18% is getting close to the water activity that makes many woods marginally microbiologically stable.
As an aside, it seems as if you were not constantly homogeneous chips; when the top chips would be dry, the bottom layer must be torrified. Thanks again, Mark -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Kana Sent: Sunday, December 19, 2010 3:32 AM To: [email protected] Subject: Re: [Gasification] Drying fuel with IC exhaust and other pleasures... Dear Mark and all, Drying wood is a science for some people, it is for us just a necessity. We have been making furniture in Indonesia and local cottage industry, was drying wood under sun. No matter how hot the weather was, wood never go down below 18%. That was unacceptable, considering we ship furniture to Denver where relative humidity is very dry. All the furniture was getting cracked. I introduce a very simple system which was adopted by the local government as most efficient way of drying wood. Since the people using the kilns were not educated, our moisture meter was the walls! When they openned the side door for inspection, if they saw wet walls, they opened up vents for 15 minutes, or until the walls were dry again. We simply put a U steel pipe, made with 1 cm thick mild steel, on the back of the kiln, which was covered with small room built with bricks. We burned the waste wood in the room, returning air from kiln enter from bottom of the U and after heated and dried somewhat, pulled in to the kiln with the pulling force of fans. Because of humidity and heat, fans lasted about 6 months, they were cheap enough to replace until we started using special insulated motors, we also solved this problem. The kilns in my factory worked for almost 12 years with very little maintenance, since we dried wood under moisture there was not much warping and cracking. We now take the same simple principle to dry the wood chips for gasification or saw dust for briquette production. We use the heat exchanger for the exhaust gas to lower the heat, to make sure we will not have fire. Mark, you are absolutely right, in the big hoppers, chips on the bottom will dry first, and the moisture will be rising to top. One of our projects involve drying wood chips from 30-40% down to 10%. The hopper has capacity of 120 m3. We feed the exhaust heat from the bottom and installed simple vents on top. When the moisture hits certain level, the vents open and moisture air pushed out by the force of blowers which feeds the hopper. Since we feed the boilers and gasifiers, from the bottom of the hopper ( Hopper supplies wood chips to 2 hot oil burners and gasifier) it works well for us. Because we dried to wood chips down to 15%, energy we receive is more from the chips, monthly wood chips savings are about 300 tons. For the gasifier feed, we design another system and jacketed screw feeder for drying wood chips further, since we ad a longer screw feed and this is an outside installation, we added couple of feeding points and couple of chimneys to take the moisture air out. I try to apply what I learned from the list, "The drier the wood is, the less the tar." On this joyful Holiday season, our best wishes to you and your families. Regards, Robert Kana, Biomass Energy, Indonesia _______________________________________________ The Gasification list has moved to [email protected] - please update your email contacts to reflect the change. Please visit http://info.bioenergylists.org for more news on the list move. Thank you, Gasification Administrator _______________________________________________ The Gasification list has moved to [email protected] - please update your email contacts to reflect the change. Please visit http://info.bioenergylists.org for more news on the list move. Thank you, Gasification Administrator
